In the field of thermal printing, it has been found desirable to transfer energy to a dye donor from a laser through an optical fiber. Additionally, it has been found desirable to use a plurality of lasers and optical fibers to generate an image with a plurality of simultaneously produced dots. A thermal printer that operated in this mode is described in U.S. Patent Application Ser. No. 451,655, entitled "Thermal Printer", filed Dec. 18, 1989, pending. This application has a common assignee with the present application.
When operating a thermal printer such as the one described above, it is necessary to accurately focus light from output ends of the optical fibers onto a dye honor. In order to facilitate this focusing, it is desirable to have all of the output ends of the optical fibers in a single and well defined plane.
Additionally, it is important that each of the output ends of the optical fibers is accurately spaced a well defined distance from adjacent output ends. When the spacing of the output ends is well defined, the thermal printer can accurately produce images with high resolution. This is because image data can be reliably assigned to particular optical fibers for transfer to a particular area of a receiver of the image.
In one version of the thermal printer described above, an image is produced with a resolution of 1800 dots per inch. The image is generated in a series of multi-line swaths with a separate optical fiber transferring energy for each of the lines during printing. Each of the swaths may contain as many as twenty print lines. Therefore a print head for the printer must contain as many as twenty output ends of optical fibers. Each output end must be positioned extremely close to the adjacent output end. Without extremely close positioning, a resolution of 1800 dots per inch would not be attainable.
Assembly of a print head with such a closely spaced array of optical fibers has heretofore been possible only with time consuming manual techniques that have required an inordinate amount of specialized adjustments and a great deal of trial and error. Prior art print heads have not been suitable for inclusion in a printer that is intended for low cost applications. These print heads have been too expensive and unreliable for application in printers that are to be manufactured and sold for use in typical office settings.
It is desirable therefore to provide a print head with an optical fiber array that is easy to assemble and which has a plurality of output ends of optical fibers positioned in a well defined spatial relationship to one another.